Basically, she has grassed up her friend's boyfriend for snogging someone else. The boyfriends sister has now threatened dd, nothing specific, but just if you don't keep your nose out, you'll regret it, kind of thing.
Dd is now convinced she is going to be found by this girl and attacked, and says she darent go out into the town in case. She wants this girl warned off by the police.
This isn't something I have experience of, any advice would be most appreciated.